This shell has remarkable varieties in the colouring pattern and in the ornamentation and this is the reason for several variety names with no taxonomic value. The typical sculpture is made by several spiral little ribs, often irregular ones, that sometimes change in undulating transverse folds. However such a sculpture is not much strong or it can be completely absent. In the young shells, up to 2 mm in diametre, the typical rounded holes are not yet defined; in the adult specimens they can be some tens too, of which 7-8 only are opened, while the other ones are closed by the deposit of the molluscs internal mantle. It mainly feeds on algae, scraped by the radula. Above all this species is active during the night, since it is heliophobe. The reproduction is effected at the beginning of the Summer period. The average measures are abt. 50-60 mm.

Shell ear-shaped with very low spire; 5-7 small openings with out-turned lips lie in a spiral along the last whorl and are continued up the spire as a series of closed tubercles. Aperture very large; inside of shell with bright mother-of-pearl sheen. Foot without an operculum.
The shell has 3-4 rapidly expanding whorls marked with many fine spiral lines. The aperture is oval, the outer lip with a sharp edge, the inner lip turned inwards to form a narrow shelf. Pinkish when young with light and dark mottling or bars; older shells are darker, reddish brown or greenish. Up to 90 mm long, 65 mm broad, and 20 mm high.
The head is small and flattened, carrying two long tentacles each with a bluish eye on a stalk on the outer side of its base. Cephalic lappets form a fold across the head dorsal to the tentacles. The mantle edge is thickened and warty and slit under the row of holes in the shell. The foot is large and powerful, with an oval sole; its sides are papillated ventrally and carry a thick epipodial ridge dorsally which has a scalloped edge. Many tentacles project from between the lobes. The posterior end of the foot bears transverse ridges and grooves on its dorsal surface. Brown or greenish, with darker and lighter blotches, sometimes alternating to give stripes on the epipodium which match the pattern of the shell and the substratum on which the animal lives.

Common all over the Mediterranean, mainly in the rocky infralittoral algae-covered, up to 15 m depth. This species lives in the littoral and submerged areas, often under the stones, sticking to the rocks with its strong foot (which is green, wide and with many lateral tentacles), camouflaging, since its back is often algae and crusts-covered.

H. tuberculata lives on rocky shores in the Channel Islands and Brittany, but not the British or Irish mainland, though recently imported to the latter commercially. Elsewhere ormers occur south to the Mediterranean, Azores, and Canary Islands. They are found from extreme low water to depths of about 40 m, feeding on encrusting algae.